Hot sandwiches are ideal for convenience foods in many ways, they can be quickly prepared, quickly consumed, utensils are not required and basic ingredients from a reasonable selection can be combined in countless variations to provide a wide variety of appetizing sandwiches. However, the perfect convenience food could be prepared before it is needed, stored, then served almost immediately after the customer places his order. In this respect, hot sandwiches fall short of being perfect convenience foods, as it is difficult to provide a suitable but inexpensive and ecologically sound environment for maintaining hot sandwiches in palatable condition for the storage interval between preparation and consumption, particularly for periods of more than several minutes. Styrofoam clamshells have been used but many who are concerned about the environment feel that the clamshell requires too much volume in landfill, is not at all biodegradable and is quite difficult to economically recycle. Further, they only provide for rather limited storage periods. However, they do protect the sandwich from physical deformation rather well while the top gives the customer a convenient spot for french fries or onion rings.
More recently, composite sandwich wraps have been introduced which are considerably more effective in controlling moisture and keeping hot sandwiches at proper temperature, while overcoming or reducing many of the ecological problems associated with clamshells. These three layer wraps comprise an absorbent inner layer, a foldable, printable outer layer and a moisture-vapor-impermeable barrier layer in between wherein at least one of the interior or exterior layers are discontinuously bonded to the moisture-vapor-impermeable layer to form pockets which communicate with each other allowing flow of air between pockets defined between the layers by the discontinuous bonding pattern. These wraps have proven to be quite effective in keeping many types of sandwiches warm while avoiding soggy spots on the bun. In some cases however, especially for sandwiches containing large portions of meat or having multiple meat patties, these wraps may not be capable of absorbing all of the moisture given off by the patties, particularly if the sandwich is stored for several minutes longer than the usual holding time. In other cases, the buns or cheese may adhere to the absorbent inner layer detracting from the attractiveness of the products as either detached paper will need to be removed from the sandwich or portions of sandwich will detach and be scattered over the wrap. If the wrap does not retain all of the moisture given off by the sandwich, the bun may become easily deformed as a result of excess moisture absorbed. The sandwich wrap of the present invention provides greatly improved moisture control while decreasing adhesive tendencies between sandwich components and the absorbent inner layer by interposing a foraminous hydrophobic water-vapor-permeable pellicle on fibers positioned between the sandwich and the moisture-vapor-impermeable polymeric layer. Surprisingly, we have found that moisture control properties remain even if the entirety of absorbent portions of the wrap interior to the moisture-vapor-impermeable layer is provided with the foraminous-hydrophobic water-vapor-permeable pellicle. In preferred embodiments, highly absorbent materials are included in at least a portion of the absorbent layer between the pellicle bearing fibers and the water-vapor-impermeable film. We use the word "pellicle" to describe the "deposit" or "precipitate" left behind after hydrophobe precursor has been applied to fibers and the carrier removed. We chose the word "pellicle" because it has the connotation of being very thin and not necessarily continuous. As will be seen, release and hydrophobic properties can result from extremely thin pellicles which do not necessarily encompass the entirety of the surface of the fiber.
1. Field of the Invention
This invention relates to improved composite wrap materials, and more particularly to composite wrap materials used primarily for packaging hot foodstuffs as well as for similar hot finger foods such as tacos, burritos and the like, with the composite wrap providing an improved combination of heat retention, moisture control and masking of food staining, this combination of properties providing both improved appearance upon serving and unwrapping (usually termed "presentation") and palatability of sandwiches which may have been stored for somewhat over a quarter of an hour. The invention also relates to a method of making the improved composite wrap materials.
2. Background of the Invention
Recently introduced composite wraps alleviate many of the grease and moisture control difficulties experienced with conventional commercial wraps such as polyethylene coated paper, hot melt coated paper, foil/tissue laminations, dry wax, and the like. These newer composite wraps (prepared according to pending U.S. patent application Ser. No. 07/372,165 abandoned in favor of continuing application Ser. No. 07/759,717, now U.S. Pat. No. 5,128,182) largely overcome many moisture and grease control problems, especially for single patty hamburgers and cheeseburgers but in the case of sandwiches evolving particularly large amounts of steam or grease, a sacrifice of heat retention or storage time (holding period) could be required to avoid problems due to excessive moisture and grease evolved. Upon prolonged holding, especially large amounts of moisture are typically evolved from sandwiches having multiple patties or those containing portions which evolve especially large amounts of moisture, such as over about four ounces of hamburger or so. Thus, there is presently a need to develop a further improved composite wrap capable of transcending the aforementioned trade-off, bringing to larger sandwiches advantages that first generation composite products brought to the smaller. In addition, there is a need to develop a method of manufacturing these improved composite wrap materials.